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package bjc.utils.funcutils;
import java.util.LinkedList;
import java.util.function.Predicate;
import bjc.data.ITree;
import bjc.utils.funcdata.FunctionalList;
import bjc.utils.funcdata.IList;
/**
* Implements various utilities for trees.
*
* @author Benjamin Culkin
*/
public class TreeUtils {
/**
* Convert a tree into a list of outline nodes that match a certain
* path.
*
* @param tre
* The tree to outline.
* @param leafMarker
* The path to mark nodes with.
* @return The list of marked paths.
*/
public static <T> IList<IList<T>> outlineTree(ITree<T> tre, Predicate<T> leafMarker) {
IList<IList<T>> paths = new FunctionalList<>();
LinkedList<T> path = new LinkedList<>();
path.add(tre.getHead());
tre.doForChildren((child) -> findPath(child, path, leafMarker, paths));
return paths;
}
/* Find a path in a tree. */
private static <T> void findPath(ITree<T> subtree, LinkedList<T> path, Predicate<T> leafMarker,
IList<IList<T>> paths) {
if(subtree.getChildrenCount() == 0 && leafMarker.test(subtree.getHead())) {
/* We're at a matching leaf node. Add it. */
IList<T> finalPath = new FunctionalList<>();
for(T ePath : path) {
finalPath.add(ePath);
}
finalPath.add(subtree.getHead());
paths.add(finalPath);
} else {
/* Check the children of this node. */
path.add(subtree.getHead());
subtree.doForChildren((child) -> findPath(child, path, leafMarker, paths));
path.removeLast();
}
}
}
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